Question

Flight muscles of birds are attached to
(a)Keel of the sternum
(b)Clavicle
(c)Coracoid
(d)Scapula

Answer 1

This is often one among the foremost important which is additionally referred to as breast bone and characteristic skeletal elements in living birds. This bone is analogous to the bone where all ribs connect. About six ossifications that together form this structure.

Complete answer:
The sternum which is also known as breastbone which is present axially along the midline and extends outward, which is perpendicular to the plane of the ribs. The keel of the sternum provides support to which a bird's wing muscles attach, thereby providing adequate leverage for flight. Keels don't exist on all birds; especially, some flightless birds lack a keel structure.

Additional Information: -Birds even have a reduction in bones, e.g. teeth. Birds‘ entire anatomy and physiology is tailored for efficient flight, but not all birds are capable of flight.
-Soft down feathers trap still air on the brink of the surface of the body, thermally insulating a bird.
-Contour feathers on the body establish the graceful, streamlined contour of a bird's body, and therefore the enlarged flight feathers form the aerodynamic surfaces of the wings and tail.
-Featherless areas, the beak, and feet, are covered with relatively thick, heavily cornified epidermis: rhamphotheca on the beaks and podotheca on their feet.
-These cornified cells produce beta-keratin and therefore the calcium deposited between keratin proteins generally makes this covering hard and powerful.
-Skeletal adaptations lend strength to the skeleton in order that the thrust or forward force generated by the wings can cause a maximal lift.
-Some of the vertebrae and a few bones of the pelvis of birds are fused into one structure, as are some finger and leg bones - all of which are separate in most vertebrates.
-The skeleton of birds is remarkable for the rapidity of its ossification and therefore the light and stylish mechanism displayed within the adaptation of its several parts.
So, the right answer is, ‘Keel of the sternum.’

Note: -Most birds are morphologically very similar because they're constrained by the stress of flight. -Birds have light skeletal systems or pneumatized bones, light and powerful musculature, and high metabolic rates.
-Most birds can fly; their forelimbs are modified into wings; which distinguish them from most other vertebrate classes.
-Birds have scaly legs and feathers.