A．Titles are “down”, with only the first letter of their first word capitalized no matter what your target journal is.
B．Titles are “up and down”, with main words capitalized no matter what your target journal is.
C．Title are “up”, with all the letters capitalized no matter what your target journal is.
D．The guidelines to the authors of your target journal are the best directions for you to make the decision. So follow them strictly.