Which recommendation is most appropriate for the hypertensive individual training to improve cardio respiratory endurance?

35% VO2 reserve is below the minimum threshold needed to elicit a cardiorespiratory training effect and would not meaningfully improve endurance.

95% HR reserve is near-maximal intensity and can cause acute, dangerous blood pressure elevations that are contraindicated in hypertensive individuals.

Swimming at 65% VO2 reserve falls within the moderate-to-vigorous intensity range (40-70% VO2 reserve) recommended for hypertensive clients by ACSM. The aquatic environment provides hydrostatic support that reduces cardiovascular strain compared to land-based exercise, and this intensity level produces cardiorespiratory adaptations without triggering the dangerous acute hypertensive response associated with high-intensity or heavy isometric work.

Circuit weight training involves isometric and high-resistance components that can provoke sharp pressor responses, making it a less appropriate primary modality for hypertensive clients even at 55% HR reserve.