Identify the techniques used to try to locate extra solar (exo) planets

A) transits

B) doppler technique

C) spectral detection

D) gamma cepheid

the doppler technique

Explanation:

The doppler technique was an indirect method for finding extrasolar planets and brown dwarfs from radial-velocity measurements using observation of Doppler shifts in the spectrum of the planet's parent star.

A Transits

B Doppler technique

Explanation:

The techniques used for the location of extra solar planets are both transit method and the Doppler technique. Extra solar planets are those that orbit a star other than the Sun of our solar system.

Transit method uses the method of measuring light curve from the stars and the reduction of the brightness over time is noted. This is an indirect method.

Doppler technique is a much more reliable method to discover exoplanets. It is also called wobble method. This is much more reliable to detect exoplanets. When there is no exoplanet for a given star, the Doppler shift pattern does not change. If exoplanet exists, it changes.