This question distinguishes the two standard power measures used to describe a pulsed radar transmitter. A pulsed radar does not transmit continuously; it emits short bursts (pulses) of RF energy and then listens for echoes during the much longer silent interval, repeating this at the Pulse Repetition Frequency (PRF).

The two terms fill the blanks as follows, giving Peak; Average as the correct answer:

• Peak power (P_t): the maximum instantaneous power delivered during the pulse width (τ). It is deliberately made very high because detection range depends on the energy concentrated in each pulse.
• Average power (P_av): the mean power computed over the entire pulse repetition period T = 1/PRF, which includes the long off-time between pulses. Because the transmitter is off for most of the cycle, the average power is much lower than the peak power.

They are linked through the duty cycle:

P_av = P_t × (τ / T) = P_t × Duty Cycle

Since τ ≪ T in radar, the duty cycle is small (often well under 1%), so P_av ≪ P_t.

Why the other options are wrong:

• Average; Peak reverses the two definitions — the maximum instantaneous value during the pulse is the peak, not the average, so the order is incorrect.
• Pulsed; Continuous and Effective; Gain are not the standard radar power terms; "gain" describes antenna directivity, and "effective/continuous" do not name the instantaneous-during-pulse versus mean-over-cycle pair the question defines.