Option a: multiply
by 4.
Explanation:
The expression is 
Dividing the two fractions which is the same as multiplying the first fraction by the reciprocal value of the second fraction.
Hence, it can be written as

Hence,
is the quotient.
Option a: multiply
by 4.
To determine the quotient, let us multiply the term
by 4, we get,

Hence,
is the quotient.
Thus, Option a is the correct answer.
Option b: multiply
by 
To determine the quotient, let us multiply the term
by 4, we get,

is not the quotient. Since, the quotient is
which is not equivalent to
and hence we cannot multiply
by 
Hence, Option b is not the correct answer.
Option c: multiply
by 
To determine the quotient, let us multiply the term
by
, we get,

is not the quotient. Since, the quotient is
which is not equivalent to
and hence we cannot multiply
by 
Hence, Option c is not the correct answer.
Option d: multiply
by 4
To determine the quotient, let us multiply the term
by 4, we get,

10 is not the quotient. Since, the quotient 10 which is not equivalent to
and hence we cannot multiply
by 4.
Hence, Option d is not the correct answer.