Answer:
A. Step-up voltage transformers have fewer turns in the primary than in the secondary winding.
Step-by-step explanation:
A step-up transformer is a transformer that transform a lower voltage in input into a higher voltage in output.
The transformer equation states that:
![(V_p)/(N_p)=(V_s)/(N_s)](https://img.qammunity.org/2020/formulas/physics/high-school/xu6e5x53v9mwvrylzesw8xvxd1iok5gil2.png)
where
Vp is the voltage in the primary winding
Vs is the voltage in the secondary winding
Np is the number of turns in the primary winding
Ns is the number of turns in the secondary winding
we can re-arrange the equation as
![(V_p)/(V_s)=(N_p)/(N_s)](https://img.qammunity.org/2020/formulas/physics/high-school/gmhdooznprvs2kfw0ipf4n63z806p0b8v3.png)
For a step-up voltage,
![V_s > V_p](https://img.qammunity.org/2020/formulas/physics/high-school/xd7czeqt3yt6z5h27yhq4fydvcbhs0ake8.png)
so
![(V_p)/(V_s) < 1](https://img.qammunity.org/2020/formulas/physics/college/118i7o8e17xzh30hb7be01al7yfulvil53.png)
which implies also
![(N_p)/(N_s)<1\\N_s > N_p](https://img.qammunity.org/2020/formulas/physics/college/c2tzo4wl191gc9qe68oqpez7s5ncexzsrp.png)
so, the primary winding has fewer turns than the secondary coil.