Which transformation causes the described change in the graph of the function y = cos x?

the transformation results in a horizontal shrink.
the transformation results in a vertical stretch.
the transformation results in a horizontal stretch.
the transformation results in a vertical shrink.

Although your question is incomplete a general answer is provided using th function y = cos x .

To stretch a function you will have to multiply it by a value that is either greater than one ( 1 ) or a value that is less than -1  while

To shrink a function we multiply the function with a value that is either greater than -1 or less than one ( 1 )

Note :  when shrinking or stretching a function horizontally we multiply every variable x with the shrinking/stretching factor

when shrinking or stretching a function vertically we multiply the whole function by the factor which we intend to shrink or stretch it by.

hence the various transformation that causes the described change are as listed above ( answer )

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the answer is c

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