Final answer:
The transit photometry method (B) is currently the best-suited technique for finding Earth-like planets, as it allows detection of smaller planets that cause a dip in brightness of their host star when they pass in front (transit). Unlike the radial velocity method which favors larger planets and direct imaging best for young gas giants, transit photometry can detect Earth-sized planets, especially with data from space-based observatories like Kepler.
Step-by-step explanation:
The best-suited technique currently for finding Earth-like planets is B) Transit photometry. The transit photometry method involves measuring the diminutive dip in brightness that occurs when a planet passes in front of its star (a transit), relative to the observer. This method has proven effective in finding smaller planets like Earth that orbit their stars more closely, thanks to space-based telescopes like the NASA Kepler space observatory. Although the radial velocity method has been useful in detecting the presence of exoplanets through the gravitational wobble they cause in their host stars, it is more sensitive to larger planets. Direct imaging, on the other hand, works best for young, large gas giant planets that emit a substantive amount of infrared light. Gravitational microlensing can reveal planets as their gravity bends the light of a more distant star, but it's a rare event and not suited for finding a specific type of planet repeatedly.
If a planet is found via transit photometry and can also be measured using the radial velocity method, researchers can ascertain both the mass and size (and therefore density) of the exoplanet, giving us a clearer picture of its composition. Nevertheless, direct detection remains a formidable challenge due to the faintness of reflected light from an Earth-sized planet and its proximity to the bright glare of its host star.